In oncology, for treating cancer tumors, it is necessary to infuse fluids which may be very aggressive. The preparation of these fluids, which appear as a solute, may prove to be dangerous for the caregiver in so far that they are very aggressive and may be the source of accidents with toxic or allergic effects. In many cases, the drug which has to be administered appears in the form of powder in a vial in vacuo, which is obturated by a plug with an elastomeric membrane.
In order to mix this drug contained in such a vial in vacuo to a fluid intended to be infused, in a first phase the drug has to be diluted as a powder in this liquid by means of a syringe generally equipped with a needle. The fluid to be infused may for example be saline (distilled water+NaCl).
The plug with an elastomeric membrane of the vial is then crossed with the needle, which has the effect of causing sudden entry of air into the vial which was in vacuo. This air mixes with the drug as a powder and may partly emerge therefrom by carrying away the pure drug, which is dangerous for the caregiver responsible for the preparation. Once the needle of the syringe has been put into place through the plug with an elastomeric membrane, the caregiver responsible for the preparation pushes by means of the syringe the fluid to be infused into the vial, which there again causes the initially confined air to emerge in the vial loaded if required with still not yet diluted drug particles.
The vial is then shaken and the mixture is sucked up through the plug with an elastomeric membrane by means of the syringe. In practice, the liquid mixture to be infused plus the diluted drug is injected and sucked up several times in succession out and into the vial with the syringe, in order to thoroughly mix the drug in the liquid. However, such a mixture causes inflows and outflows of air from the vial, which implies risks of pollution for the caregiver responsible for the preparation on the one hand and for the prepared mixture on the other hand.
Finally, the needle is taken out of the vial. It then has to be disconnected from the syringe without pricking anybody and avoiding any direct contact of the thereby produced mixture with the caregiver responsible for the preparation. The filled syringe is then connected near the patient to an infusion bag connected to the latter or directly connected to the actual patient.
During this handling, the main causes of an accident are related to sealing problems towards liquids and gases from the inside of the vial towards the outer medium, with dissemination of dangerous products, which may come into contact with the skin, the eyes and the respiratory system of the preparation and care personnel, but also to sealing problems of the outer medium towards the inside of the vial which risk contaminating the preparation, or further to problems of vertical stability of the interfacing device. It may prove to be necessary that the preparation personnel operate in confined spaces, under a hood or in enclosures, and with thick gloves.
Such interfacing devices are already known. For example, document FR 2 928 539 proposes an interfacing device comprising air circulation means, intended to allow inflows and outflows of air from the vial to be perforated, provided with air filtration means adapted for retaining the pure drug particles still not diluted during the air outflow from the vial, as well as of impurities contained in the ambient air penetrating into the vial upon air inflow into the vial. The device therefore gives the possibility of making the handling safe and preparing the mixture.
However, the use of this device causes several inflows and outflows of air into the vial which further pose safety problems. Indeed, the filtration means, which is generally in the form of an escape filter, is highly sensitive to liquids and its filtering does not seem to be sufficiently efficient for the users.
Moreover, the device is relatively complex to make and comprises a large number of parts.
In document FR 2 951 648, an interfacing device is therefore proposed, comprising a base on which is attached an air tank via air circulation means, in which the air tank comprises a rigid cell associated with a flexible membrane, defining a compartment isolated from the outside world. This improved air circulation system then replaces the filter and allows circulation of air in the vial, while maintaining the vial isolated from the outside and therefore risks of contamination by outer elements.
Such an interfacing device has good functionalities and gives the possibility of efficiently limiting the risks of contamination. However, its design is highly expensive and complex. Moreover, this design does not give the possibility of sampling the whole of the fluids in the vial.
Subsequently, in document FR 2 982 484 a more stable interfacing device was proposed in all the positions and during handling operations. This device retains the closed air circulation system but proposes another means for attaching the base to the vial through a hooking-up means of the harpoon type rather than a snap-on plug. For this, FR 2 982 484 proposes an interfacing device intended to establish a connection between a fluid-injection instrument and a vial to be perforated, comprising:                a suitable base for connecting the interfacing device to the fluid-injection instrument,        a means for attaching the base on the vial to be perforated, arranged at a distal end of the interfacing device, having a divergent proximal end forming a shoulder and a suitable convergent distal end for facilitating penetration of the attachment means into the vial to be perforated, wherein the attachment means comprises at least one notch in an area adjacent to its proximal end suitable for establishing a fluidic communication between the vial to be perforated and an external space of the interfacing device.        
This device clearly improves the ergonomics of the device. However, its design remains relatively expensive and complex.
In document WO 2007/120641 an interfacing device has also been proposed, comprising a base configured so as to be connected to an injection instrument on the one hand and to a vial to be perforated on the other hand. However, the device described in this document is very complex to apply, insofar that it proposes the introduction of a sachet into the vial during the perforation in order to compensate for pressure differences. The presence of such a sachet in the vial however risks disturbing the operator during successive suctions and re-injections for mixing the contents of the vial with the fluid, preventing the full taking up of the fluid and possibly having sealing problems.
Document WO 97/20536 as for it describes a device for preparing a drug solution reconstituted from two components. However, in this document, the pressure differences are compensated by means of a particle filter which, as this has been seen above, is highly sensitive to liquids and is not sufficiently efficient in the eyes of the users.